It is common practice in a networked computer environment for a computer user to collaborate on a document with another user on the network. Such a network may be a local area network (LAN), wide area network (WAN), the Internet or the like. In such a collaboration, each user may create and edit an electronic file by using a software application such as general application software, software designed specifically for the type of file that is the object of the collaboration, or the like.
A collaboration may be made possible by maintaining a master version of the electronic file in a location that is accessible to all users who will be collaborating on the file. In a conventional networked computer environment, there may exist a server computer and one or more user computers. The server is accessible to each user computer and therefore may store and control the master version of the file being collaborated on by the users.
When collaborating on an electronic file, a user accesses the file on the server. The user may then work on the file by altering the file in any way made available to the user by the application. For example, if the application is a word processor, spreadsheet, database, and/or the like, the application may provide means for performing tasks such as appending to, editing, copying, and/or deleting the file. At the completion of any alterations, the user may save changes to the version of the file stored on the server if the user wishes to retain such alterations to the file and has the requisite permissions.
While having a centrally-stored file is good for collaboration, requiring access to the server has a downside. A user must be connected to the server in order to access the server copy of the file. Replication engines are used to solve this problem. Such engines allow the user to have a local copy of the file on the server. This local copy allows the user to work with or view the file even when the server copy is not accessible. The replication engine manages the replication of the server state of the file to the user's local machine, giving the user offline access while attempting to maintain consistency between the server copy and the local copy.
This solution, however, has drawbacks, however, and such consistency is difficult or impossible to maintain using existing replication engines. The version of the file on the server computer may change while the user is not connected. For example, the version of the file on the server may be version A. This version A is copied to the user's computer by the replication engine. When the user is “offline” (disconnected from the server), the user edits the file, producing version B. Meanwhile, a second user edits the server copy of the file, creating version C. When the user again connects to the server, the user will have access to the user's current version (B) and the server version (C). Current replication engines provide only the ability to copy the user's version over the server version, in which case the second user's changes are lost, or to copy the server version over the user version. No information is available for the user regarding changes from version A. If the user synchronizes by saving version C and abandoning changes, version B will no longer be accessible to the user.
Because of these drawbacks, an improved way of managing replicated files from a server is desirable.